Electric furnace and method of operating same



(No Model.) 2 Sheets-Sheet 1.

A. H. GOWLES. ELECTRIC PURNAGE AND METHOD 0F OPERATING SAME.

No. 583,249. Patented May 25,1897.

2 Sheets-Sheet 2.

Patented May 25,1897.

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A. H. COWLES.

ELECTRIC EUENAGE AND METHOD 0E QEEEATING SAME.

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UNITED STATES PATENT OEEICE.

ALFRED II. COWLES, OF CLEVELAND, OIIIO, ASSIGNOR TO THE ELECTRICSMELTING AND ALUMINUM COMPANY, OF ILLINOIS.

ELECTRIC FURNACE AND METHOD OF OPERATING SAME.l

SPECIFICATION forming part of Letters Patent No. 583,249, dated May 25,1897. Application filed July 6, 1895. Serial Nm 555,115. (No model.)

To all whom, it may concern:

Be it known that I, ALFRED Il. COWLES, a citizen of the United States,residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented certain new and useful Improvements in Electric Furnaces and inMethods of Operating the Same and Controlling the Ore ReductionsTherein; and I do hereby declare the following to be a full, clear,

io and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

The object of the present invention is to effect the reduction andsmelting of ores in an electric furnace or the reduction of anycompounds capable of being treated in an electric furnace in a moreuniform way than has been heretofore practiced and to secure moreperfect reductions and results.

The admission of a gas or of a gas or vapor producing fluid into anelectric furnace has heretofore been practiced, but the gas or the fluidor material producing the gas within the chamber has always beenintroduced and 2 5 passed through the furnace-chamber in a uniformdirection, and the flow of the gas within the chamber Where the latteris charged with a body of ore or of a material or mixture of differentmaterials to be treated has always been 3o constant whenever it has beengiven any di rection, and the effect of the steady flow of gas throughsuch a mass in a uniform direction tends to elevate the temperature ofthe mass on the side of the outflow of the gas 3 5 and to lower it onthe side of the inflow.

I will not in the present case consider in detail the special effects ofthe reversal of the gas iiow within an interstitial mass, but willpresent the particular features incident to 4.o the present applicationof the invention.

In the accompanying drawings, Figure 1 is a vertical sectional View ofan electric furnace; and Fig. 2, a horizontal section of the same, takenon the line 2 2.

A is a furnace-chamber lilled with a charge B of mixed broken granulatedore and carbon or ore alone or other material or mixture capable ofbeing reduced or treated in the furnace. For the purpose of the presentinven- 5o tion it matters not what the charge may be so long as it is acharge of material to be subjected to electric heat and to the action ofthe gas flowing through or over its mass.

C is an electrode leading down into the mass, the bottom of thefurnace-chamber or the reduced material forming the other electrode.This electrode is ad j ustably supported in any preferred way. Forexample, the upper end c' of the holder is screw-threaded and engageswith a hand-wheel nut c2, properly supported in a girderc. One of theelectric cables is attached to the holder at ci. Provision is made forcooling the carbon-holder by means of a flow of water therethrough. Thelower part of the holder is made hollow and provided with a water-pipec, leading into the bottom of the hollow chamber within the rod, andwith a water-discharge pipe c at the upper end of the same. Thefurnacechamber or crucible is also provided with a water-jacket a andwith water-pipes d2 d3 for the inflow and outflow of water therefrom.The structural features of the water-cooled carbon-holder abovedescribed are made the subject of a divisional application hereof.Electrical connection is shown as made with the outer iron shell of thefurnace at d, the current passing through the carbon filling or block A'to the charge in the furnace-chamber. Extending out laterally onopposite sides of the furnace-chamber, and at a sufficient distanceabove the bottom of the same to form a sump D below, there are thelateral flues, passages, or pipes E E, diametrically opposite andleading outward through the furnace-walls, and these flues are filledwith coarsely-granulated or broken carbon e, the interstices of thesaine forming carbon-lined passages for the gas. Connected with theseflues E E are the gas-pipes F F', respectively, properly protected bywater-jackets ff', said gas-pipes leading into the reversing-valvechamber G, which chamber has a gas-supply pipe II and a discharge-pipeI. The latter may, for example, lead to a gas-holder, or to suchapparatus as maybe proper for the subsequent treatment or handling ofthe product. Connected with the gas-supply pipe II there is anair-supply pipe I I', which admits air under pressure to the gas, andthe supply of air can be regulated and controlled by the valve 71.

IOO

The furnace-chamber, as indicated, is filled to the top with the chargeof ore and carbon, with the top covered over with a surface covering offine carbon b. This is a sufficient closing in of the furnace-chamberfor cases where the gas-pressure is light, but the ehamber may becompletely closed in and sealed when necessary.

K is a tap for drawing off the molten material collected in the sump.Access is gained to the flues E E', for cleaning them out and forfilling them with coke, by removing the caps K K on the ends of thepipes.

In operation, a furnace having been charged and heated up to a workingtemperature by means of the electric current, the gas is turned on andthe air-valve 7L is opened to a proper extent to feed into the gas arequisite amount of air for action in the furnace-chamber. A current ofgas iiows through the passage F E, for example, into thefurnace-chamber, passing through the interstiees of the ore-body andthrough the central field of heat, where the reduction of the ore, orthe chemical change in the charge of the furnace, takes place, or themajor portion of the same is effected, that being the field of thegreatest electrical energy.

The mixing of air with the gas produces a combustible mixture whichburns within the interstices of the ore-body and adds to the heatedfield the heat due to the combustion of the gas, and in this way theelectric heat is supplemented and increased by the heat of combustion.

A current of gas passing through the furnace-chamber flows outwardthrough the passage E and the interstices of the carbon c, filling thesame, and through the pipe F and the proper channel in thereversing-valve G and the discharge-pipe l. The current of hot gassespassing through the central intensely-heated field to and through theflue E gradually extends the field of heat in the direction of thispoint of exit, while the inflowing current of gas cools the oppositeside of the chamber, and if the flow of gas is long continued in onedirection it gradually7 works the side of the sphere or zone of heatinward toward the center of the mass. The center of the zone of highestheat, barring an arc center, by reason of the carrying inward of theheat on the inflowing side and the carrying outward of heat on theouttlowing side, is being gradually moved toward the point of exit ofthe gas or products of combustion from the chamber. The particles ofsoot, dust, and sublimated matter picked up and carried along by thegas-currents are, on the inflowing side, carried inward toward thecenter of greatest electrical activity and the region most favorable forchemical changes and reductions in the ore-bodies, thus clearing out andopening up the channels for the free passage of the gas through the masson that side. On the side of exit the gas-currents as they get away fromthe heating-Held deposit within the interstices of the mass and of theexit-passage the dust, soot, and sublimated powders carried by them.After the gas has been flowing through the furnace for a proper intervalof time the reversing-valve Gis shifted, making connection of thegas-supply pipe ll with the pipe F' and of the pipe F with thegas-discharge pipe l. The flow of gas is now through the furnace-chamberfrom the flue F to the flue E in the opposite direction from what it hasbeen flowing and in an opposite direction through the interstices of theore-body.

The effects above set out occur now in the opposite direction. The areaof intense heat, which extended laterally toward the flue E', now movesinward and travels toward the new point of exit-the flue lil-and thedeposit of fine matter in the interstices of the mass is carried backinto the heated field, while the formation of new deposits in theintersticos of the mass on the opposite side and in the flue E may begoing on. Thus with a proper periodical reversal of the gas-valve itwill be seen that there is secured a perfect control of the field ofheat in the furnace, and it can be either held central, by making thereversals of the flow sufficiently frequent, or it can be caused to movefrom side to side at command. Moreover, the regenerative principle comesinto play. lith each successive reversal of the gas-flow the materialthrough which the gas passes before it enters the zone of electricalheat becomes hotter and hotter and the inflowing gas enters the field ofaction at a constantly increasing temperature. rlhe electric heat isthus supplemented not only by the heat of combustion but by what wouldotherwise be waste heat recovered and utilized by the reversal of thegas-flow.

The movement of the field of heat is the most marked in an incandescentfurnace where there is no fixed arc center. rllhe heat can then bebunched and the center of greatest heat moved along the line of the flowof the gas through the mass to the point of exit and then caused totravel back again. If a charge of ore is of an elongated form with thegas inlet and exit passages at the ends, the field of concentrated heator bunch of highest heat can be made to travel toward the point of exitand to concentrate close up to that point, and then by the reversal ofthe direction of the flow of the gas through the charge the bunch of highestheat can be made to traverse the length of the charge to the otherend, and thus travel back and forth. The electrical heat action on theorc charge and the action or reduction due to the gas is thus undercontrol, and more perfect results are obtainable than is possible whensuch control is wanting.

l am aware that in combustion-furnaces it has been proposed to pass aiiow of gas through a body of incandescent fuel for the purpose ofchanging the composition of the gas, and also to reverse the flow of thegas IOO IIO

through the fuel, but this is not donc for the purpose of controlling aheat center produced otherwise than by the gases themselves, nor isthere any other heat present.

Vhat I claim as my invention isl. The method of treatment of ores orother compounds or mixtures of material of low conductivity hereindescribed, which consists in passing an electric current and generatingwithin the mass of the material electrical heat, and in periodicallypassing gas therethrough in opposite directions, as and for the purposeset forth.

2. The combination in an electric furnace, of an electric-furnacechamber with gas inlet and outlet flues or passages and a reversingvalve connected with the said inlet and outlet flues or passages andadapted to change the direction of the flow of gas through theelectrically-heated field of the furnace-chamber, as and for the purposeset forth.

3. In an electric furnace, a furnace-chainber adapted to be charged atthe top and having a central adjustable electrode extending down intothe chamber, lateral gas inlet and outlet flues or passages, openinginto the furnace-chamber and filled with granulated or broken carbon,together with gas connections with said inlet and outlet ilues orpassages for the supply of gas to the furnace-chamber and the removal ofthe same therefrom, as and for the purpose set forth.

Ll. In an electric furnace, a furnace-chamber, adapted to be charged atthe top, and having a central adjustable electrode extending down intothe chamber, lateral gas inlet and outlet flues or passages opening intothe furnace-chamber and filled with granulated or broken carbon,together with gas connections with said inlet and outlet fines orpassages for the supply of gas to the furnace-chamber and the removal ofthe same therefrom, and means for reversing the flow of gas through theinlet and outlet fines, as and for the purpose set forth.

5. The combination in an electric furnace of an electric-furnacechamber, having electrical connections for the passage of an electriccurrent through the same, of pipes connected therewith for the inflow ofgas and air and for the outflow of gas, and means for the reversal ofthe direction of the flow of gas through the electrically-heated fieldof the furnace-chamber, as and for the purpose set forth.

G. The combination in an electric furnace of an electric-furnacechamber, having electrical connections for the passage of an electriccurrent through the same, of pipes connected therewith for the inflowand outflow of gases, a reversing-valve in operative rela-- tion to saidpipes to reverse the vliow of gas through the electrically-heated field,and an air-pipe connected with the gas-supply pipe outside of thereversing-valve, as and for the purpose set forth.

In testimony whereof I hereto affix my signature in presence of twowitnesses.

ALFRED H. COVLES.

Vitncsses:

Giras. M. Voncv, WM. G. TAYLOR.

